In semiconductor technology, gallium nitride (GaN) is used to form various integrated circuit devices, such as high power field-effect transistors, metal insulator semiconductor field effect transistors (MISFETs), high frequency transistors, and high electron mobility transistors (HEMTs).
In a conventional semiconductor device, gate structures are formed using fluoride-based plasma treatment techniques; however, such techniques suffer control issues for a device having plural enhanced mode (E-mode) or depletion mode (D-mode) transistors or devices on the respective circuit. Therefore, a compound semiconductor gate structure and method of forming such a gate structure are needed.